Photographically light-sensitive silver halide-diazide colloid layers

ABSTRACT

705,842. Photosensitive materials. KALLE &amp; CO., AKT.-GES. Feb. 19, 1951, No. 4025/51. Class 98(2) Silver halide together with a water-soluble salt of a diazido compound having symmetrically arranged azido groups in a hardenable colloid such as fish glue, gelatine, polyvinyl pyrrolidone or polyvinyl alcohol is used as light sensitive layer on a base such as tracing cloth or paper, or cellulose acetate foil to constitute an intermediate reproduction material from which prints can be made, or on a base of metal to constitute a replacement of chromate-glue layers as used in lithography, the claims being restricted to the use of a ratio of diazido salt to colloid of not less than 1:4 and to the presence of not more than 1 per cent of alkali metal halides in the layer, restrictions necessary for satisfactory results. Exposure is under a negative and development with an alkaline metal-hydroquinone solution unexposed parts of the layer being washed off with cold or warm water before or after development to leave a black silver image in tanned colloid. Examples describe precipitation of stoichiometric proportions of silver nitrate and potassium chloride into a solution of glue, addition of 4 : 41 - diazidostilbene - 2 : 21 - disulphonic acid sodium salt or of the corresponding dicarboxylic acid, coating of this emulsion (without chilling and washing), exposure and development as indicated above. Specifications 401,898 and 452,745 are referred to.

Patented Dec. 22, 1953 PHOTOGRAPHICALLY LIGHT- SEN SITIVE- S-ILVER HALIDE-DIAZIDE COLLOID LAYERS Maximilian Karl Reichel and Wilhelm N'eugebauer, Wiesbaden-Biebrich, Germany, assignorsxto Keuffel & Esser Comp., Hoboken, N. J

No. Drawing, Application October 13,1950, Serial No. 190,042;

(Jl ims pri ri y, pplication Germany October 24, 19.4.9

8. Claims.

The. present invention relates. to a type of photosensitive material commonly used as; an intermediate reproduction material in the drafting art. This photosensitive material is commonly used to make duplicate tracings: from which prints can be made by the ordinary reproduction methods The particular type of material to which the invention relates is made by coating on a suitable; base a colloid layer (such as glue) containing a silver halide and an agent capable of hardening or tanning the colloid under the influence of light. The base for this type of photosensitive. material is ordinarily tracing cloth which has. been waterproofed by means or a nitrocellulose lacquer; However, tracing paper and' other suitable materials. may also be used as a base.

Photosensitive'. materials of the type described are exposed to light'under. a negative; original (usually a brown-print-made. from. a. tracing) andv washed with water to. remove the colloid layer from th unexposed areas; They are then de.- veloped with a photographic developing solution to form a black: silver relief? image, of,- the exposed areas.

Chromates have; been used as. the hardening agent for the colloid in the photosensitive material of this type known in the art. However, the stability of the materials containing chromates has long beenv recognized as, not. being as. good asdesirable. It was-therefore necessary to take special care in storing such materials and. even then they could not be. prepared too; long a time before use.

Chromatesare; also generally used in, other photosensitive layers; e. g. those used in litho-. graphy. These: layers contain colloids such as glue but do not contain silver halides; Many: attempts have been made to replace; the poison-- ous' chrome salts in this latter typeof photosensitive layers with other substances which would have the same: hardeningaction, on 001 loids upon exposure to light; Particularly light sensitive diazo compounds: whose. light decomposition products are able. tot-an colloids; (U. S.

Patent No. 2,100,063), IlitI'OndBl'iVfi-tiVBSf of polyhydroxy compounds (U. S. Patent No. 2,090.4 570) and aromatic aldehydes, such; as: anisaaldehyde, have been proposed as substitutes for chromatesz. 'More recently aromatic azides hav also: beencompounds, (as compared to. those containing chromates) arev characterized by a highly improved shelflife. Nevertheless, satisfactory results were not obtained when aziclo compounds were first used in colloid layers containing silver halides. The reason for this is probably that the presence of inorganic salts in colloidal layers inhibits to a large extent the performance of the tanning or hardening of the colloidal substance and that the tanning action may even be compensated completely by high concentrations of said compounds. For these reasons, photosensitive colloid layers containing silver halides in which azido compoundsare used in place of chromates have not. beenv introduced into practice.

The principal object of the present invention is to increase the, shelf life of light sensitive photographic layers containing colloid substances and silver halides by substituting aromatic azido compounds for the di-chromates conventionally used as hardening agents for the colloid.

The. azido, compounds which have been found to be useful in colloid layers. containing silver halides are. diazidostilbene compounds in which the azido groups are symmetrically arranged. The ratio of the weight of the diazido-stilbene to the dry weight of the colloidal substance should not be less than 1:4. The optimum ratio has been found to be about 1:3.

It is also important. that there should not be a large excessv of alkali metal halide present in the colloid layer. An alkali metal halide is usually used in combination with silver nitrate in order to form the silver halide in the colloid. The simplest way' in which to make sure that there will not be a large excess of alkali metal halide is' to add the alkali metal halide and silver nitrate to the colloidal dispersion in substantially stoichiometric proportions or with. only a slight excess of alkali metal halide.

For" the; purpose; of" the present invention the diazido-stilbene compounds. used must be soluble in water. Hence it follows that diazido-stilbenes are suitable. which can easily be transformed into water soluble compounds, for example, into salts. Diazido-stilbenes. of this kind are diazido- StllbBIlGrSUlfOJ-llq acids. and diazido-stilbene-carboxylic acids, both with two symmetrically arranged azid'o groups in the molecules, such for example, as 4,4-diazidostilbene- ,2-olisulfonic acid" and 4,4"-diazidO-stilbene-ZB'-dicarboxylic acid. These acids are used preferably in the form of their alkali metal salts.

The base-material used to support the new colloid layers made according to the present invention may be identical with the base-material ordinarily used in the art (i. e. waterproofed tracing cloth). However, foils of cellulose acetate, metallic plates, metallic foils particularly those which may be subjected to a surface-treatment, such as surface oxidation, surface-roughening and so on may also be used to carry these photosensitive layers. The colloidal substances which may be used in the new process are also the same as those known in the art: 1. e., fish glue, gelatine, polyvinyl-pyrrolidone, polyvinyl alcohol and so on. They may be u sed separately or in combination with each other.

' The new light-sensitive layers, produced in accordance with the present invention containing sufficient quantities of diazidcstilbene compounds in place of chromates as the tanning agent, are far superior to the hitherto known colloid layers containing silver halide and chromate of like tanning capacity and light-sensitivity, especially with regard to their shelf-life in the light sensitive state and they are at least equal to the known products with regard to tanning power and sensitivity to light.

These photosensitive layers free from chromate offer a further advantage insofar it is possible to use also more transparent supports than tracing cloth, such as superficially saponified acetyl cellulose which is less suitable for chromate silver halide colloid layers under like work ing conditions.

Photosensitive material coated with colloid layers containing chromate and silver salt, when stored for a lcn period of time, even under the most favorable conditions, forms, after exposure to light and development with a soda alkaline metol-hydroquinone solution, black layers of imely distributed silver spread over the whole surface of the image. Said black silver layers are very difficult to remove without damaging the image. The chromate-free photographic colloid layers in which in accordance with this invention diazidostilbene compounds are used as tanning agent have not the above described disadvantage. They develop clear and need only a treatment with running tap water in order to remove the developer solution prior to the drying of the copy.

The following examples are inserted to illustrate the invention.

1. To an emulsion consisting of 5 liquid ounces of Le Pages photographic glue,

and '7'? liquid ounces of distilled water are slowly added dropwise while under constant stirring out of two burettes a. 9 liquid ounces of silver nitrate solution (3.0? ounces by weight of dry salt in distilled water) and b. 9 liquid ounces of potassium chloride solution (1.43 ounces by weight of potassium chloride dissolved in distilled water).

4 moved with running tap water. The silver image is then developed with an aqueous soda alkaline metol-hydroquinone solution consisting of 4 grams of metol,

12 grams of hydroquinone,

12 grams of sodium carbonate (free from water), 44 grams of sodium sulfite (crystallized) in sufiicient distilled water to make a total volume of 2250 cc. A black silver image on a clear background is obtained. The black silver image is distinguished by an excellent absorption power for short wave length light.

This light-sensitive material free from chromates has unlimited stability and is distinctly different from the hitherto known colloid layers containing silver halide and chromate.

2. The same photosensitive glue-gelatin colloid layer containing silver salt is used as described in Example 1, but in lieu of 2 ounces of 4,4-diazidostilbene-2,2'-disulfonic acid sodium salt, 2 ounces of 4,4-diazidostilhene-2,2'-dicarboxylic acid sodium salt are added.

3. The same photosensitive colloid described in Example 1 is coated on a saponified cellulose acetate foil having a saponified surface and after drying it is exposed to light under a negative pattern. Thereafter those areas of the colloid layer not exposed to light are washed off wlth' running tap water, and developed with the aid of the aqueous soda alkaline metol-hydroquinone solution. A black silver image on a clear white background is obtained.

After having fully described and explained our present invention, what we claim is:

1. As a new article of manufacture light-sensitive material comprising a suitable base material and a light-sensitive colloid layer substantially free of alkali metal halides on said base material said light-sensitive colloid layer comprising a light hardenable solloid, silver halide and a water-soluble salt of a diazido compound selected from the group consisting of diazidostilbene-sulfonic acids and diazido-stilbcne carboxylic acids with symmetrically arranged azido groups, the ratio of the weight of said salt of said diazido compound to the dry weight of said light hardenable colloid being not less than 1:4.

2. As a newarticle of manufacture light-sensitive material comprising a suitable base material and a light-sensitive colloid layer substantially free of alkai metal halides on said base material, said light-sensitive colloid layercomprising a light hardenable colloid, silver halide and an alkali salt of 4,4-diazido-stilbene-2,2- disulfonic acid, the ratio of the weight of said diazidostilbenedisulfonlc acid sodium salt to the dry weight of said light hardenable colloid being not less than 1:4.

3. As a new article of manufacture light sensitive material comprising a suitable base-material and a light-sensitive colloid layer substantially free of metal halides on said base material, said light-sensitive colloid layer comprising a light hardenable colloid, silver halide and an alkali salt of 4,4'-diazidostilbene-2,2-dicarboxylic acid, the ratio of the weight of said diazidosti1- benedicarboxylic acid alkali salt to the dry weight of said light hardenable colloid being not less than 1:4.

4. As anew article of manufacture light-sensitive material comprising a waterproofed tracing cloth base material and a light-sensitive colloid layer substantially free of alkali metal halides on ..said base material, said light-sensitive colloid layer comprising a light hardenable colloid, silver halide and a water soluble salt of a diazido compound selected from the group consisting of diazido-stilbene-sulfonic acids and diazido-stilbene carboxylic acids with symmetrically arranged azido groups, the ratio of the weight of said salt of said diazido compound to the dry weight of said light hardenable colloid being not less than 1:4.

5. As a new article of manufacture light-sensitive material comprising a cellulose acetate foil having a saponified surface as a base material and a light-sensitive colloid layer substantially free of alkali metal halides on said saponified surface of said cellulose acetate foil base material, said light-sensitive colloid layer comprising a light hardenable colloid, silver halide and a water soluble salt of a diazido compound selected from the group consisting of diazido-stilbene-sulfonic acids and diazido-stilbene carboxylic acids with symmetrically arranged azido groups, the ratio of the weight of said salt of said diazido compound to the dry weight of said light hardenable colloid being not less than 1:4.

6. The process for the production of light-sensitive material capable of producing a black silver relief image comprising the steps of adding substantially stoichiometric quantities of alkali metal halide and a soluble silver salt to an aqueous dispersion of a light hardenable colloid, adding in the form of a water soluble salt a diazido compound selected from the group consisting of diazido-stilbene-sulfonic acids and diazido-stilbene-carooxylic acids with symmetrically arranged azido groups to said colloid dispersion, the ratio of the Weight of the diazido-stilbene compound to the dry weight of the light hardenable colloid being not less than 1:4 and coating said aqueous dispersion on a base material to form a photosensitive colloid layer thereon.

'7. The process for the production of light-sew sitive material capable of producing a black silver relief image comprising the steps of adding substantially stoichiometric quantities of alkali metal halide and a soluble silver salt to an aqueous dispersion of a light hardenable colloid, adding an alkali salt of 4,4-diazido-stilbene-2,2'- disulfonic acid to said colloid dispersion, the ratio of the weight of the diazido-stilbene compound to the dry weight of the light hardenable colloid being not less than 1:4 and coating said aqueous dispersion on a base material to form a photosensitive colloid layer thereon.

8. The process for the production of light-sensitive material capable of producing a black silver relief imag comprising the steps of adding substantially stoichiometric quantities of alkali metal halide and a soluble silver salt to an aqueous dispersion of a light hardenable colloid, adding an alkali salt of 4,4-diazido-stilbene2,2'- dicarboxyic acid to said colloid dispersion, the ratio of the weight of the diazido-stilbene compound to the dry weight of the light hardenable colloid being not less than 1:4 and coating said aqueous dispersion on a base material to form a photosensitive colloid layer thereon.

MAEHMILIAN KARL REICHEL. WILHELM NEUGEBAUER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,564,161 Weingarten Dec, 1, 1925 1,984,090 Seymour Dec. 11, 1934 FOREIGN PATENTS Number Country Date 886,716 France July 12, 1943 232,145 Switzerland Aug. 1, 1944 

1. AS A NEW ARTICLE OF MANUFACTURE LIGHT-SENSITIVE MATERIAL COMPRISING A SUITABLE BASE MATERIAL AND A LIGHT-SENSITIVE COLLOID LAYER SUBSTANTIALLY FREE OF ALKALI METAL HALIDES ON SAID BASE MATERIAL SAID LIGHT-SENSITIVE COLLOID LAYER COMPRISING A LIGHT HARDENABLE SOLLOID, SILVER HALIDE AND A WATER-SOLUBLE SALT OF A DIAZIDO COMPOUND SELECTED FROM THE GROUP CONSISTING OF DIAZIDOSTILBENE-SULFONIC ACIDS AND DIAZIDO-STILBENE CARBOXYLIC ACIDS WITH SYMMETRICALLY ARRANGED AZIDO GROUPS, THE RATIO OF THE WEIGHT OF SAID SALT OF SAID DIAZIDO COMPOUND TO THE DRY WEIGHT OF SAID LIGHT HARDENABLE COLLOID BEING NOT LESS THAN 1:4. 